1. Field of the Invention
The present invention relates to a method for preparing cooked rice with barley in an aseptic packing system.
2. Description of the Related Art
Barley can be divided by the number of kernel rows in the head, which are two-row barley and six-row barley. Barley can be further classified into hulled barley, in which the husk adheres onto the grain upon threshing, and naked barley, in which the husk easily falls free from the grain upon threshing. The barley that is commonly used in cooked rice is naked barley. The naked barley is divided into waxy barley having waxy starch such as glutinous rice and non-glutinous rice, and common non-waxy barley (whole barley). The waxy barley is divided into waxy hulled barley having a husk and waxy naked barley having no husk, in which the waxy barley has higher contents of dietary fiber and beta-glucan than common barley (non-waxy barley). The starch of waxy barley has a low amylose content and a high amylopectin content, and as a result, when it is cooked, its water binding ability is higher than that of non-waxy barley, and thus waxy barley becomes more rapidly gelatinized and swelled. Further, waxy barley has a lower gelatinization temperature, and a higher viscosity than non-waxy barley, and as a result, when it is cooked, the cooking time is shortened, the cooked rice gets waxier, and the retrogradation of the rice is delayed, which leads to reduced retrogradation tendency after being cooled.
Approximately 103 to 105 CFU/g of microorganisms are present in the barley, and approximately 101 to 102 CFU/g of sporing, heat-resistant microorganisms are also present in the barley. In the case of cooked rice which is cooked and eaten daily at home or in plants, heat-resistant microorganisms are not harmful. However, if the cooked rice is intended to be stored and transported at ambient temperature over a long period of time, the proliferation of such heat-resistant microorganisms become significantly harmful. In particular, if common microorganisms or sporing, heat-resistant microorganisms are present in the trough portion of the barley, it is difficult to kill the microorganisms even when sterilizing the cooked rice with barley in an aseptic packing system, unlike the microorganisms in the hull.
Therefore, many studies have been made in order to control the heat-resistant microorganisms that are present in the trough portion of the barley in the preparation of cooked rice with barley in an aseptic packing system. In Japan, cut polished barley (barley that is divided into two portions in the trough direction), or rolled barley (barley that is pressed through a roller after permeation into a high-temperature vapor) has been used to prepare cooked rice with barley in an aseptic packing system. However, these products do not have native appearance of barley, and still have a problem in that the unique texture of barley cannot be tasted by the user.
Further, Korean Patent Application Publication No. 10-1997-64404 describes a method for preparing sanitized rice in a can (cooked rice, or cooked rice with barley in a can), which specifically comprises the steps of putting rice, barley, and beans with water into a can; steaming the mixture on a conveyor using high-pressure steam at about 100° C.; adding a predetermined amount of boiling water to the can which is passed through the conveyor and capping the can with a lid for sealing treatment; subjecting the processed can to treatment in cooling water under drastically reduced pressure, and then to high-pressure sterilization in a high-pressure steam furnace at about 120° C. for about 25 minutes for completion of the sterilization treatment to remove soil bacteria or other bacteria in the rice; and finally subjecting the can to pressurization treatment in a rapidly cooling furnace, thereby the contents of the can being vacuum-treated. However, in this Patent, the control of microorganisms in the starting raw materials is insufficient, and thus, there is an urgent need to ensure that long-term storage of rice and barley is safe.
Accordingly, many studies have been actively conducted so as to attain a safe long-term storage of rice and barley by minimizing the level of microorganisms in the starting raw materials during the preparation of cooked rice in an aseptic packing system. By way of one example, Korean Patent Granted No. 10-228509 describes a method for preparing cooked rice with various cereals which can be stored for a long period of time, comprising the steps of soaking various cereals such as red bean, millet, Indian millet, and black rice in a calcium salt solution at a concentration of 0.2 to 0.8%, and minimizing the level of microorganisms by heat treatment at 100 to 121° C. for 20 to 40 minutes. Korean Patent Granted No. 10-528491 describes a method for preparing cooked rice with nutritious ingredients which can be stored for a long period of time, comprising the steps of adding an aqueous organic acid solution at a concentration of 0.1 to 0.3% to an aqueous calcium solution, and soaking ginseng, jujube, chestnuts, black rice, and the like in the resulting solution, thereby reducing the initial level of microorganisms.
However, if the methods for controlling the microorganisms in the starting raw materials as described in the above-described Patents are employed for cooked rice with barley in an aseptic packing system, there are problems in that heat-resistant microorganisms that are present in the trough portion of barley are insufficiently controlled, and in that the unique texture of barley cannot be tasted by the user.
Under these circumstances, the present inventors have conducted studies on a method for pre-treating barley as a raw material, which can remarkably reduce the initial level of microorganisms that are present in barley as the raw material, while solving the problem in which the user cannot taste the unique texture of barley. As a result, they have found that cooked rice with barley in an aseptic packing system, which is obtained by using barley that has been first gelatinized and then retrogradated, has a reduced initial level of microorganisms in barley, leading to excellent stability against microorganisms, as well as good qualities such as soft and flexible texture, taste, and flavor that are similar to those obtained by a domestic conventional cooking method, thereby completing the present invention.